Javig,
The word trinity does not appear in the scriptures. It was coined by the early church fathers to help explain a very difficult concept which is exactly what the nature of God is.
We have God the father, God the Son and God the Holy Spirit. Each of these three are clearly mentioned in scripture. The trinity is used to show that they are all in complete union with one another and are part of what makes up the one God. God's very nature and essense is that he is 3 persons (for lack of a better word) that equal the sum total of one God. Just like we humans have three parts according to scripture, mind, body and soul, that make up our one self.
But the fact is that the exact word trinity does not appear in the text. And even with this teaching, it is still difficult for us to grasp the concept of God and his nature. He is infinite in his wisdom but we are not.
Its ok if we do not fully grasp the idea of the trinity because Jesus never said we must understand this in order to be saved. Our faith is in Christ and his attoning sacrifice for our sins, not in the trinity doctrine. So it is not essential to our faith in Christ. You know even Paul struggled with areas of understanding, for instance he stated that we (including himself) could not fully understand the breadth, or depth or length or God's love for us. But he knew God loves us and loves us greatly.
So understanding every point of scripture or doctrine of the church is not what is important or essential to our salvation. What is, is that we know and believe that Christ died for our sins. Like Paul said he preached "Christ cruxified", that is what is foremost of importance for Christians. Not a doctrine that was developed much later. Peace, Lilly